Steven Kantecki, 43, and his wife Sarah Kantecki, 39, deceptively stole the man's life savings over an eleven month period.
Hull Crown Court heard how the couple, from Ramshill Road, Scarborough, leered the man into a false sense of security claiming they were the two people he could count on and trust as his carers.
In reality, they deceived him by stealing £196,000 from him.
In that time they overindulged at the elderly man's expense by buying designer goods.
The couple were found guilty of theft following a trial at Hull Crown Court and were yesterday sentenced to a combined total of nine years and six months in prison.
Sarah Kantecki was also found guilty of perverting the course of justice.
Detective Sergeant David Porteus, of Humberside Police, said: “The only place the Kantecki’s deserve to be is behind bars, so this sentencing is welcomed.
“Fraud can be an extremely distressing offence to become a victim of, especially when the level of offending is of this magnitude.
“I hope that today’s result will provide the victim’s family with some comfort in knowing that they can no longer cause harm to vulnerable people in the community.
“Sometimes people may feel embarrassed that they fell for a ‘scam’ and choose not to report fraud or seek advice about it.
“Please remember that anyone can be a victim of fraud. Fraudsters constantly reinvent themselves to find new ways of tricking people.
“If you think you might have been a victim of fraud, report it to Action Fraud by visiting actionfraud.police.uk or by calling 0300 123 2040. Alternatively, call Humberside Police on 101. In an emergency or if a crime is in progress, dial 999."